Intra-oral dental x-ray film is used in general dentistry and by some specialists. By necessity, these films must be small in order to be placed inside of the patients' mouth. Furthermore, the objects being radio-graphed, the patients' teeth, are also small. Consequently, the dental images are exceedingly small, making diagnosis and patient case presentation utilizing these x-ray films a difficult task. After obtaining the x-rays films, the dentist must examine them in order to determine if there are dental diseases to be treated. For example, the dentist identifies dental caries by noting dark (radiolucent) areas on the x-ray image, checks the bone density and levels, examines the roots and nerves of the teeth, checks the position and development of the teeth, looks for lesions such as cysts or tumors, assesses damage when trauma occurs, and monitors periodontal conditions. All assessment and diagnosis must be determined on a set of very small films, each of them has a standard size of 1 inch by 1.25 inch, or 1 inch by 3 inch. In the conventional practice, this is accomplished by clipping the film to a dental x-ray viewer light box for back-lighting the film for visual inspection. Although the x-ray film has very high resolution, the information revealed often is not sufficient for diagnosis or monitoring a dental treatment because of its small size.
With the advance of the digital image technology, several different types of devices have been developed to produce digital images of the intra-oral x-ray film for visual inspection by the dentist, and communication with the patients.
In one approach, direct digital imaging is used to provide enlarged digital images on a display screen. This technique utilizes a probe equipped with an x-ray sensing charged coupling device (CCD). During a dental examination, the probe is placed inside a patient's mouth, upon exposing to a small dose of x-rays, the image formed on the CCD device is sent to a computer where it is processed. The processed digital image can then be viewed on a computer screen, and can be manipulated and printed. To date, this is an exceedingly expensive technique, and the produced digital images do not have the same image clarity and quality of the x-ray film. Furthermore, as the digital image produced depends on the algorithm and software used by instrument, reliability of information provided still remains questioned by the dentists and the regulatory authorities. Up to date, none of these instruments has received U.S. Food and Drug Administration's approval as a diagnostic instrument.
In an other type of approach, several devices have been disclosed in the prior art, which capture images from the x-ray film by a video camera, and uses the digital images for displaying. Among most of them, the captured digital images are post processed by a computer using various digital processing techniques. U.S. Pat. No. 5,995,138 (to Beer, et al) teaches capturing the image from dental x-ray film through the use of a video camera. The digital image obtained by the video camera is sent to a computer to be digitized, for facilitating communication between dentists and insurance companies. U.S. Pat. No. 4,013,833 (to Zimmerman) teaches to use a video camera to capture x-ray film images projected onto a target plate.
U.S. Patent Application Publication No. 2006/0038141 A1 (Blume) teaches an apparatus for converting a standard dental x-ray view box into an analog or digital viewing system. The apparatus includes a Y-axis track and a X-axis track attached to the chassis of a standard dental x-ray view box, and a CCD video camera attached to the Y-axis track. The CCD video camera is movable in both Y and X axes for capturing images from multiple x-ray films clipped on the x-ray view box. The image is directly transmitted to and displayed on a monitor. As the CCD video camera is positioned very close to the x-ray films by the tracks, a quarter inch thick ruby-clear acrylic filter is used to reduce the intensity of the back light emitted from the x-ray view box. With this device, the back lighting of the x-ray view box directly sheds on to the camera, which causes poor contrast of the digital images produced. Furthermore, as can be appreciated, with such a shorter working distance, a substantial distortion of the digital image is inherent. Moreover, this typically produces an image with a focused center portion, but blurred edge portions, therefore, not the entirety of the enlarged image can be used for the purpose of diagnosis.
Commercially, a x-ray film viewer produced by DENTAMERICA™ is available under the product name Telerex Video X-ray Film Viewer. This device uses a video camera to capture the image of a standard x-ray film, which is transmitted directly to a TV or computer monitor for displaying an enlarged image. It is an inexpensive, compact equipment with a height of 9.4 cm. However, the quality of the digital images produced is poor. The enlarged digital image has blurred edges, and only the center of the x-film is in focus. In terms of the usefulness for diagnosis, only the distal portions of the image can not be used. For example, if the x-ray film has an image of five teeth, the teeth at the distal portions where the image has more distortion and poor resolution, can not be used by the dentist. Furthermore, this device uses a horizontal spring loaded film tray for carrying the film into the housing of the instrument. However, the film tray obstructs the edges of the x-film from displaying.
Based on the above, it is apparent that there is need for an inexpensive, reliable x-ray film viewing device which provides a substantially enlarged and undistorted digital image of the entirety of a standard intra-oral x-ray film with sufficient quality for diagnosis.